The invention relates to a brake pad for a disk or drum brake, which brake pad is composed of a brake pad carrier and a brake material layer which is fixed thereto and which, during a braking operation, comes into contact with a brake face of the brake.
The braking action is based on the friction effect since, during the braking process, the brake pads are pressed against the brake face. In the case of a disk brake, the brake face is a disk which rotates with the wheel, while in the case of a drum brake, the brake pads which are configured in the shape of segments are pressed against the inner face of the brake drum. The brake material layer is formed into a slab in the case of a disk brake, and into a circular segment in the case of a drum brake.
Brakes are safety-relevant components, and therefore quality control of the components of a brake is an important aspect. For safety reasons, it is additionally necessary to check the brake pads at predefined intervals. It is additionally extremely important that the production process, in particular of the brake material layer, can be traced at any time. For this reason, the brake calipers or the brake housings are normally provided with type plates. It is important that the identification features remain readable even after a relatively long period of use of the vehicle. The type plates are preferably produced from a corrosion-resistant material and are, where possible, attached to protected points of the brake or of the vehicle.
The brake material layers are produced from a non-magnetic material whose friction coefficient is relatively high in order to obtain a high braking force. The brake material layer is attached to the brake pad carrier during the course of production. The brake pad carrier is conventionally produced from steel.
In the case of the brake pads according to exemplary embodiments of the invention, the designation of the brake pad is stamped onto a pad carrier plate. The precise batch designation of the brake material layer is, in contrast, often only printed on, since such batch designation is only established once the brake material has been pressed onto the support plate, and embossing is then not possible, since there is the risk of the brake pad carrier bending, which could cause the brake material layer to become detached.
It has been shown that the printed-on batch designation of the brake material layer is often no longer readable or not even present after just a short period of use on the vehicle, in particular where the brake pads are subjected to relatively high thermal loading or vibration loading. One practice which is conventionally already used is to record the precise batch designation of the brake material layer by a so-called “needling-on” operation. However, the above-specified problem is still present even with this method, since the individual needle points cannot be formed very deep into the material, and can therefore disappear under the action of corrosion or friction.
In order to solve the above-stated problem, one may wish to have a plate designed in the manner of a type plate to likewise be attached to the brake pad. A plate of this type cannot, however, be attached to the surface of the brake pad carrier, since that face is required, at least in the case of a disk brake, for introducing the application force. In addition, a plate which is attached in such an exposed manner would not be protected from damage.
The following exemplary embodiments of the invention include configuring a brake pad such that the precise batch designation of the brake material layer is readable over the entire service life of the brake.
In one example, the brake pad carrier is provided with an aperture, or with a cutout which is situated on that side which faces toward the brake material layer, into which is inserted a badge which displays pad-specific information.
The cutout or the aperture which is formed in the brake pad carrier makes it possible for the badge to be attached at a protected position, so that the badge is not subjected to any damage. In this way, the contained information, for example numbers and/or letters, is readable at all times. The production of the aperture or of the cutout can take place in a simple manner during the manufacturing process in the course of the production of the brake pad. Since the badge is situated within the brake pad carrier, it is accommodated at a protected position, so that no wear or damage occurs. The cost expenditure is negligible, since the material requirement for the badge is extremely low.
A brake for which the pads according to the invention are particularly suitable is presented by EP 0 531 321.
In one preferred embodiment, the badge is embodied as an embossed badge. The information to be displayed is then formed by a generally known embossing process, with the highest possible depth being possible for the numbers and letters and any necessary symbols. The embossing process can likewise be introduced in the simplest possible manner into the manufacturing process of the production of the brake pad. Conventional equipment can be used for the embossing process, since it is provided that the hardness of the badge material is lower than the hardness of the brake pad carrier.
The service life of the brake pads of a vehicle, in particular of a commercial vehicle, is relatively high. In order that the information on the badge can be easily read after a relatively long period of use, it is provided that the badge is composed of a corrosion-resistant and temperature-resistant material. A material of that type may be, for example, aluminum.
In one example, the brake pad carrier may be provided with a cutout, having a depth great enough that the badge is situated completely within the cutout, that is to say the elevations which are situated facing toward the brake material layer project beyond the contact face, between the brake pad carrier and the brake material layer, toward the interior of the brake pad carrier. In exemplary embodiments where the brake pad carrier is, in contrast, provided with an aperture, the aperture should be of stepped design, with the greatest cross section being situated facing toward the brake material layer. This exemplary arrangement defines a contact face for the edge region of the badge. Although the edge region may also be fixed to the contact face, for example by using adhesive bonding, this is not strictly necessary, since a closed chamber is formed as a result of the stepped design of the aperture.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.